Std::isalnum(std::locale) (3) Linux Manual Page

std::isalnum(std::locale) – std::isalnum(std::locale)

Synopsis

Defined in header<locale>

    template <class charT>

    bool isalnum(charT ch, const locale &loc);

Checks if the given character classified as an alphanumeric character by the given locale’s std::ctype facet.

Parameters

ch – character
loc – locale

Return value

Returns true if the character is classified as alphanumeric, false otherwise.

Possible implementation

  template< class charT >
  bool isalnum( charT ch, const std::locale& loc ) {
      return std::use_facet<std::ctype<charT>>(loc).is(std::ctype_base::alnum, ch);
  }

Example

Demonstrates the use of isalnum() with different locales (OS-specific).
// Run this code

#include <iostream>

#include <locale>

int main()

{
    const wchar_t c = L'\u2135'; // mathematical symbol aleph
    std::locale loc1("C");
    std::cout << "isalnum('ℵ', C locale) returned "
              << std::boolalpha << std::isalnum(c, loc1) << '\n';
    std::locale loc2("en_US.UTF-8");
    std::cout << "isalnum('ℵ', Unicode locale) returned "
              << std::boolalpha << std::isalnum(c, loc2) << '\n';
}

Output:

isalnum(‘ℵ’, C locale) returned false
isalnum(‘ℵ’, Unicode locale) returned true

std::isalnum(std::locale) (3) Linux Manual Page